Loud speaker



06L 1933. A. w. D. HARRIS LOUD SPEAKER Filed April 16. 1932 2 Sheets-Sheet l INVENTOR ARTHUR WE [:[ARRB ATTORNEY Oct. 31, 1933.

A. w. D. HARRIS 1532, 159

LOUD SPEAKER Filed April 16. 1932 2 Sheets-Sheet 2 Patented Get. 31, 1933 UNITED STATES PATEN FICE LOUD SPEAKER Arthur W. D. Harris, New York, N. Y., assignor to Patent Engineering Corporation, a corporation of Delaware Application April 16, 1932. Serial No. 605,560

12 Claims.

This invention relates to improvements in loud speakers and has for an object the provision of a loud speaker capable of faithfully reproducing all tones in the audible scale.

Another object of the invention is the provision in a loud speaker of driving elements of two different characters, one having characteristics in favor of the higher tones and the other in favor of the lower tones.

A further object of the invention is the provision of a loud speaker having such elements connected to individual diaphragms which are disposed substantially parallel to each other.

Other objects and advantages of this invention will be apparent to those skilled in the art.

Loud speakers of the electro-magnetic or dynamic type reproduce the tones in the lower register more faithfully than those in the higher register, and piezo-electric or salt crystals reproduce tones in the middle and higher register more fathfully than those of the lower register.

This invention contemplates the combination in a loud speaker of a reproducer of each of these two types so that more faithful reproduction of all tones may be obtained.

In one embodiment providing a compact unit, two cones are used and they are mounted substantially parallel to each other, the rear one being driven electro-dynamically and the front 30 one driven by means of a crystal. The construction is further simplified by passing the member connecting the crystal to its associated cone through the core of the dynamic driver.

Referring to the drawings:

Figure 1 is a vertical sectional View of the improved loud speaker;

Figure 2 is a front elevation of the device;

Figure 3 is a rear view of the device;

Figure 4 is a View of the crystal showing the movement thereof; and

Figure 5 is a diagram showing how the two driving elements are connected to the output of a radio set or amplifier.

A bracket having a circular opening 11 r therein forms the main support for the elements of the device. A yoke 12 has a core 13 secured thereto and carries an electro-magnetic winding 14. Ths yoke is secured to the bracket 10 in any suitable manner with the core 13 substantially concentric with and extending into the opening 11.

The diaphragm member 15 at one'extremity carries a voice coil 16 preferably of cylindrical form and is mounted so that this voice coil is positioned between the inner surface of the opening 11 and the outer surface of the core 13 in an intense magnetic field furnished by means of the winding 14.

The diaphragm 15 shown for convenience in the form of a cone has its outer rim clamped between the members 1'7 and 18 by means of screws 28.

The member 17 is preferably an annular ring of channel or L cross section suitably secured to the bracket 10 by any suitable means such as screws 19.

The member 18 is preferably in the form of a frustrum of a cone with a flanged annular portion 20 integral therewith and having a bezel p 21 for locating the same in concentric relation to the member 17.

The other end 22 of the frustrum is also flanged and of annular form, substantially parallel to and of smaller diameter than the annular portion 20 and forms a support for a second diaphragm 23.

This diaphragm 23 may also be in the form of a cone and may be mounted parallel to the diaphragm 15 with its outer rim 24 clamped between the end 22 of the frustrum and the clamping ring 25 by bolts 26.

Openings 27 are provided in the slanting surface of the frustrum shaped member 18 to allow the sound from the diaphragm 15 to pass out into the surrounding air.

The core 13 has a central hole 29 throughout its length.

A support plate 30 is secured to the yoke 12 in any suitable manner and has clamped thereto a crystal element 31 consisting of either piezoelectric material or crystalline salts.

This crystal has one end thereof securely fixed onto the support plate 30 by means of a clamp member 32 and screws 33.

The other end of the crystal 31 is free to move or vibrate and has secured thereto a clamp 34 which is positively secured to a connecting rod 35.

This connecting rod 35 passes through the core 13 via the opening 29 and its other end is positively secured to the apex 36 of the diaphragm 23 so that when the crystal 31 vibrates the motion will be imparted to this diaphragm.

The diaphragm 15 driven by the dynamic voice coil 16 reproduces the lower notes more faithfully and the diaphragm 23 driven by the crystal reproduces the middle and high notes more faithfully than the dynamic unit does, so a speaker constructed according to the invention gives the best reproduction obtainable.

One modification of the device contemplates the mounting of the crystal element on the bracket 10 as shown in the dotted lines of Figure 1 in which case the push rod would not pass through the core 13 but would engage one of the crystal arms which is passed through the cone 15 in front of the voice coil 16.

The method of connecting this speaker up is shown in Figure 5. The magnet winding 14 terminating in terminals 37 may be connected to a source of direct or rectified current or may be used as one of the choke coils of the radio set. The output terminals 38, 38 of the set are connected to the primary 40 of the transformer 39 and the secondary 41 thereof is connected to the voice coil 16.

The crystal unit 31 preferably consists of two crystals cemented together with a plate 42 therebetween and two outside plates 43 and 44 thereon as shown.

The plate 42 is connected to one output terminal 38 of the set and the plates 43 and 44 are connected together and to the other terminal 38 of the set; in other words the crystal and the primary 40 are connected in parallel across the output terminals 38 of the set.

It is obvious that many changes may be made in the parts and the arrangement thereof without departing from the spirit of the invention as covered by the following claims.

What is claimed is:

1. In a loud speaker, a unitary structure including a pair of concentric diaphragms, a magnetic reproducing element adapted to drive one of said diaphragms, and a crystal reproducing element adapted to drive the other of said diaphragms.

2. In a device of the character described, a bracket having a circular opening therein, a magnetic core extending into said opening and forming an air gap therebetween, a moving coil adjacent to said core, a diaphragm carrying said movable coil, a second diaphragm adjacent to said first diaphragm, and a crystal driving element operatively connected to said second diaphragm.

3. In a device of the character described, a bracket having a circular opening therein, a magnetic core extending into said opening and forming an air gap therebetween, a moving coil adjacent to said core, a diaphragm carrying said movable coil, a second diaphragm mounted substantially parallel to said first diaphragm, and a crystal driving element operatively connected to said second diaphragm.

4. In a device of the character described, a bracket having a circular opening therein, a magnetic core extending into said opening and forming an air gap therebetween, a moving coil adjacent to said core, a diaphragm carrying said movable coil, a second diaphragm mounted substantially parallel to said first diaphragm, a crystal driving element secured to said bracket, and means connecting said crystal to said second diaphragm, said means extending through an opening in said first diaphragm.

5. In a device of the character described, a bracket having a circular opening therein, a magnetic core extending into said opening and forming an air gap therebetween, a yoke secured to said bracket and forming a support for said core, an electro-magnetic winding on said core for producing an intense magnetic flux path across said air gap, a moving coil in the path of said flux, a diaphragm supported by said frame and carrying said moving coil, a crystal driving element secured to said yoke, and a second diaphragm connected to said crystal element.

6. In a device of the character described, a bracket having a circular opening therein, a magnetic core extending into said opening and forming an air gap therebetween, a yoke secured to said bracket and forming a support for said core, an electro-magnetic winding on said core for producing an intense magnetic flux path across said air gap, a moving coil in the path of said flux, a diaphragm supported by said frame and carrying said moving coil, 2. crystal driving element secured to said yoke, a second diaphragm substantially parallel to said first diaphragm, and a driving link connecting said second diaphragm to said crystal.

7. In a device of the character described, a bracket having a circular opening therein, a hollow magnetic core extending into said opening and forming an air gap therebetween, a yoke secured to said bracket and forming a support for said core, an electro-magnetic winding on said core for producing an intense magnetic flux path across said air gap, a moving coil in the path of said flux, a diaphragm supported by said frame and carrying said moving coil, a crystal driving element secured to said yoke, a second diaphragm positioned in front of said first diaphragm, and a driving link connecting said second diaphragm to said crystal, said link passing through said hollow in the magnetic core.

8. In a device of the character described, a bracket having a circular opening therein, a hollow magnetic core extending into said opening and forming an air gap therebetween, a yoke secured to said bracket and forming a support for said core, an electro-magnetic winding on said core for producing an intense magnetic flux path across said air gap, a moving coil in the path of said flux, a diaphragm supported by said frame and carrying said moving coil, a crystal driving element secured to said yoke, a frustrum shaped supporting ring secured to said bracket in concentric relation to said diaphragm, a second diaphragm supported by said frustrum shaped support, and a driving link connecting said second diaphragm to said crystal, said link passing through said hollow in the magnetic core.

9. A device according to claim 1 in which the frustrum shaped supporting member has a plurality of apertures therein for allowing sound from said first diaphragm to pass out into surrounding air.

10. In a loud speaker, a unitary structure comprising a bracket having an opening therein, a dynamic reproducing element supported thereon, a diaphragm mounted on said bracket and adapted to close said opening therein connected to said element, a piezo-electric reproducing element supported on said first element, and a diaphragm associated with said last element and adapted to be actuated thereby.

11. In a loud speaker, a unitary structure including a pair of concentric diaphragms, a magnetic reproducing element adapted to drive one of said diaphragms and a crystal reproducing element adapted to drive the other of said diaphragms, said element including a rod passing through the core of said magnetic element.

12. In a loud speaker, a unitary structure including a framework, a diaphragm secured to said framework, an annular member secured to said framework and extending outwardly from the periphery of said diaphragm, a diaphragm mounted on said annular member, and means supported by said framework for driving said diaphragms, said means including a piezo-electric crystal.

ARTHUR W. D. HARRIS. 

